Impulse turbine



Aug. 18, 1925.

L. F. MOODY IMPULSE TURBINE Filed May 25, 1925 2 Sheets sheet l Aug. 18, 1925 1,550,090

-' L. F. MOODY IMPULSE TURBINE Filed May 23, 1923 2 Sheets-Sheet 2 To all whom itmag Patent ed Aug. 18, "1925;

UNI 1 I 1,550,090 PATENT fO FFIC E.

mwrs rnnaymoonr, or PHILADELPHIA, rrmrsnvamza;

mruiz'sn TURBINE" ao'rtcem: B e 1t known that I, LEWIS FERRY Moon'r, a CItIZGIl'Of the United States, residing at Philadelphia, in the county ofPhiladelphia and .State of Pennsylvania, have invented certain new and useful Improvements in Impulse Turbines, of which the following is a specification. I This invention relates. binesand particularly to turbines of the impulse type. The object of the'invention is 5 toprovide a turbine in which the jetwill be annular in "form so as to continuously vimpinge against all of the wheel buckets and 1n which the jet will be directed diagonally V inward so as to prevent difi'usion of the stream linesand to'maintain' the jet as a solid stream until it enters the runner;

A further object of the invention is to provide an impulse turbine in which the flow through the buckets will be spread and decelerated so as to be dischargedwith small velocity and correspondingly'small loss of energy. 7 .f In the accompanying drawings 1llustrating the invention 1 is a vertical sectional view of one embodiment in a vertical shaft turbine.

Fig., 2 is a similar view of amodification,

Figs. 3 and 4: are sections of the runner'on .lines 3-3 and 4-4-respectively of Fig. 2.

Fig.-. 5 is a vertical sectional View of a turbine showinga further modlficatlon, and

. Figs. 6 and 7 aresectional views of the runner on lines 66 and.7-7 of Fig. 5.

In the embodiment of the invention shown "in Fig. 1 the flow entering through intake I 5 is directed throughorifice 6, the stay vanes 7 infadvance of the orifice having theirsur- 'faces inclined to the radial to impart to the gflow where it leaves the orifice an inclination with respect to a plane containing the The lower edge of orifice'fiturbine axis. is formed by the renewable, stationary ring Sand the upper. edge of the orlfice 18, the

- :end 9 of the vertically movable annular plunger: 10 adjusted, for instance, by fluid I pressure'j aboveor below the piston portion a ward and inward around a complete circle 11. These edges are so arranged that the jet J from them is directed diagonally downagainst' the buckets 12 of runner 13 on shaft 14. The jet J is spaced away from both the crown 16 and shroud ring .17 of the runner, and the runner vanes may either he made of simple form with substantially to hydraulic tur- Application filed in 28, 192s. Serial no. 640,826.

' straight elements -transverse to the flow or the bucket surface may be given curvature in both dlrections, as shown in Figs. 2-4. The shroud ring 17 has no hydraulic functlon, and may be omitted if desired. When used 1t will assistin supporting the vanes against centrifugal force, and will tend to reduce the windage of the vane tips. As

shown, the turbine'isarranged with a draft tube 0 below it and passages 19,20are shown for admitting air both above and below the et J in order to insure that the jet will remain free and not fill the passages. These alr inlets may be provided with regulating valves as desired. A passage may be left between the discharge orifice of the nozzle and the entrance to the runner is small so that the alr friction of the high velocity at is reduced to a minimum. The inwardly directed arrangementof the jet J prevents a tendency for the jet to increase in cross 560- tional area normal to the lines of flow, and

thus prevents diifusion and insures-that the jet will continue as a solid stream until it enters the runner. The diagonal direction makes it poxible for. the water-to flow from the nozzle to the runner discharge without unnecessary deflection and in smooth curves,

and counteracts the tendency of the flow to a be turned wholly into the radial outward direction at the exit from the runner- The of thefiow and avoids a concentration of the flow. at the portionof the runner where 9'5 diagonal jet thus gives better distribution high relative velocity is required between the water andl' the vane surfaces. The

diagonal direction of the jet at entrance is advantageous because it thus tendsto keep the flow; as near the axisas possible while at the same time permitting .a 'sufiicient lateral spreading of the flow to provide a low discharge velocity from the runner.

The lateral spreading out and deceleration of the flow. through the buckets is provided.

for in the turbine ofthis invention and is desirable for eficient action. When the water lea es the buckets it should have alow discharge velocity, since otherwise there will be an undue loss of energy in the velocity headof the water leaving the runner. The flow should, therefore, spread out laterally as shown so that the width of the flow at discharge will be much greater than that at entrance in order to provide the necessary area of discharge. This characteristic is present in all of the turbines shown in the drawings.

, In the modification shown in Fig. 2 the lower edge 8 of the orifice 6 is made adjustable by annular plunger 10 operated, for instance, by fluid pressure above or below piston 11 so as to vary the thickness of the jet by raising or lowering its lower surface.

In this embodiment the buckets 30 are doubly curved or cup shaped, the surface of each bucket curving into and merging with the conical crown or hub 31 of the runner 32. Since the upper surface of the jet J remains in the same position for all gate openings, the water can remain in contact with the crown 31 at all gate openings. Sections of the wheel buckets 30 are shown in Figs. 3 and 4, section 3-3 being taken substantially in the direction of flow and section 4-'4 transverse to the flow at the hub 31 and in the direction of flow at the discharge. In this arrangement also a continuous draft tube could be provided if desired, the draft tube section immediately below the runner not, however, being shown in the figure. Access of air would be provided both above and below the jet, as in Fig. 1, the air passage 19' above the jet being shown and means of control being indicated by the valve 39 on the turbine casing. A renewable nozzle piece 37 at the upper lip of the nozzle is shown in this figure. The buckets 30 may be separately formed and bolted to the hub 31 if desired. The cup shape of the buckets cooperates with the diagonal inward direction of the jet J to turn the jet into the proper direction of discharge, to control the amount oflateral spreading and to provide efficient lines of flow.

In the embodiment of the invention shown in Figs. 5, 6 and 7 flow entering through the intake 35 is directed through the orifice 36, the vanes 37 and 37 in advance of the orifice having their surfaces inclined to the radial to impart to the flow where it leaves the orifice an inclination with respect to a plane containing the turbine axis. In this modification the vanes 37 adjacent the orifice 36 are movably carried by the adjustable ring member 38 forming the lower edge or lip of the orifice 36, this ring member being moved by fluid pressure, admitted through pipes 39 and 40 to opposite sides of the annular piston member 41. The buckets 50 of the runner have an extended discharge area for the jet, that is a large area transverse to the fiow lines at the discharge from the buckets so that the flow in passing through them is free to spread or widen out laterally and have a. relatively small discharge velocity when it leaves the buckets. The jet from the orifice 36 is directed diagonally downward and inward around a complete circle against the buckets 50 which are curved or cup shaped with a surface of each bucket curving into and merging with the conical crown or hub 51 of the runner. Sections of the wheel buckets 50 are shown in Figs. 6' and 7, section 66 being taken along a conical surface having elements indicated by'the line 6-6 of Fig. 5 and section 7-7 being taken along a conical surface having an element indicated by the line 7-7 of Fig. 5, each of said conical surfaces having its axis coinciding with the axis of the turbine. Air is supplied to the interior of the jet through the valve means 54 and openings as indicated at 55 just above the runner hub. Similar valve means will be provided to control the admission of air to the outer surface of the jet so that a desired vacuum may be maintained in the jet chamber by adjustment of these valve controls, it being understood that such control of the air supply is applicable to all of the turbines shown. The jet chamber in each of the figures may be similarly arranged to contain a vacuum and to act as a draft tube, being laterally enclosed and discharging below the tailwater surface. The air supply valves may either be adjusted by hand or provided with automatic control by such means as a float or an element regulated by the pressure in the draft tube; so that only enough air may be admitted to prevent the tailwater being drawn up to a level unduly near the runner, but still to preserve a high vacuum within the tube. By -maintaining such a vacuum a large part of the static head between the runner and tailrace may be utilized. In other features the turbine of Fig. 5 also corresponds in a general way to the turbines shown in Figs. 1 and 2.

In the turbine of this invention in order to obtain a very high specific speed the angle between the direction of the jet and the direction of motion of the wheel buckets at the point where the jet enters them may be made relatively large, for example, greater than 45, and the wheel bucket may be given a forward inclination in the direction of motion of the runner in order to permit a high linear velocity of the wheel buckets to be employed. In order to obtain high efficiency, the discharge area of the runner will in general be made more than double the transverse area of the jet at the nozzle and in most cases more than three or four times the jet area.

While the invention has been illustrated in connection with specific embodiments in vertical shaft turbines it is not confined to with means for forming an annular jet and directing it diagonally inward, of a runnerreceiving said jet and having buckets extending transversely across the jet.

4. In an impulse turbine the combination with means for forming an annular jet and directing it diagonally inward, of a runner receiving said jet, and means for relatively adjusting opposite edgesof said jet forming means to vary the thickness of the et.

5. In an impulse turbine the combination with means for forming an annular jet and dire. ting it diagonally inward, of a runner receiving said jet, and means to impart a whirl to said jet before entering said runner.

6. In an impulse turbine the combination with means for forming an annular diagonally inward directed jet, of a runner receiving said jet and comprising a hub portion and buckets carried thereby inclined to extend transversely across the jet.

7. In an impulse turbine the combination with means for forming an annular diagonally inward directed jet contracting after discharge from the orifice edges of said forming means, of a runner receiving said jet and comprising ahub portion and buckets carried thereby inclined to extend transversely across the jet.

8. In an impulse turbine the combination with means for forming an annular jet and directing it diagonally inward, of a runner receiving said jet, and separate air inlet means inside and outside of said et.

9. In an impuls turbine the combination with means for forming an annular jet and directing it diagonally inward, of a runner receiving said jet and having cup shaped buckets adapted to guide the stream lines as a compact mass.

10. In an impulse turbine the combination with means for forming an annular jet, of a runner receiving said jet, the discharge area of said runner being substantially greater than twice the transverse area of said jet at the nozzle.

11. In an impulse turbine the combination with means for forming an annular jet, of a runner receiving said jet having buckets the discharge edges of which have a length at least three times that of the entrance edges.

12. In an impuls turbine the combination with means for forming an annular jet, of a laterally enclosed chamber into which said jet is" directed, said chamber discharging below the level of the tailrace and a runner within said chamber receiving said "et.

13. In an impulse turbine the com ination with means for forming an annular jet, of a laterally enclosed chamber into which said jet is directed, said chamber discharging below the level of the tailrace and a runner within said chamber receiving said jet and means for admitting air to said chamber.

14. In an impulse turbine the combination with means for forming an annular jet, of a runner receiving said jet and guiding means to impart tangential components to said jet before it enters said runner, said guiding means being axially adjustable.

15. In an impulse turbine the combination with means for forming an annular jet and directing it diagonally inward. of a runner receiving said jet and means for adjusting one edge'of said jet forming means to vary the thickness of the jet.

LEWIS FERRY MOODY. 

